Is this dodgy or AIBU?

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Background: H has previous for cheating (once, a good few years ago, behaviour was dodgy at the time - glued to phone, "working late", frequently on "work dos" and staying overnight at "friends' house"). He's changed since then, relationship is much closer, he doesn't act dodgy anymore, open with his phone, no staying out etc, no behaviour concerns at all.

However I was pissing about on his phone yesterday as we were on a long car journey, I was bored, and my own phone was broken. I found an app called "wire" which is an encrypted messaging app. He had one contact on there "candyfloss85", blocked. So looks like a female, in her mid 30s, right, if 85 is the birth year? This is about the age of the woman he was previously shagging (but equally, probably about the age of quite a few of our friends). He says the contact just appeared in the app (maybe because a contact in his phone has wire and it's autoconnected?), and he blocked it because he didn't know who it was (you can't delete a contact in the app). He unblocked and messaged "who is this?". No response.

My gut says nothing's wrong, everything's fine now, he learnt his lesson, wouldn't do this again, he seems honest. But my brain says don't be a fucking mug, you didn't think he'd do it the first time, either he proves this isn't what it looks like or he can fuck off. We have 4 young kids.

AIBU or is this fucking dodgy? WWYD?

Why does he need an encrypted messaging app?

Further info, if relevant, I can see data usage for the last 30 days only. 600kb or so was used on the 6 and 7th December. No other usage. The message "Who is this?" took 1.2MB. His internet history shows he did a google search for candyfloss85 on 6th December. He thinks that usage must have been when the contact appeared and him blocking it.

His friend told him to download it for his dd and our dd to chat to each other on. I've seen that conversation. So he downloaded it onto his phone to check it out, and then downloaded it to our dd's phone.

So is his friend's daughter not Candyfloss? I wouldn't like a hidden messaging app but equally if he lets you mess around on that phone I doubt he's up to much

That sounds fine to me.

Doesn't sound dodgy to me but its a shame you have no trust in him. Obviously that is down to him.

I still don't see why he's got the app. Why does his DD need a secret app to talk to people?

My gut says nothing to worry about. He unlocked and messaged her in front of you. So I'd say probably ok. AS LONG AS the explanation about why he has Wire is absolutely true....otherwise I'd be asking why he needed it.