Why would my very well behaved 8 year old dog suddenly lose all recall and behave like a hooligan?

[parrotonmyshoulder]

He normally has perfect recall. Just now he came out of the front door while I was sorting the bins. Usually no problem if he does this. He saw another dog over the road on a lead, ran to it and wouldn’t come back. When he did decide to leave it alone, he ran to a neighbours house and tore madly around their garden. Completely ignoring me.
This has never happened before! I literally have no idea what to do!

[parrotonmyshoulder]

Never shown interest in a lady dog in his life! Or any dog at all really! Tennis balls only.
I’ll take him for a high attention/ recall focussed walk tomorrow. Usually bomb proof!
Strange.

[AvocadosBeforeMortgages]

Rather odd! Is it possible the other dog was in season?

However, if it doesn't happen again I'd be tempted to write it off as a one off moment of madness for DDog.