I didn't realise until just now you could do this, I don't know when it would have appeared, usually I just wait to click on the prize checker app (which shows from tomorrow).
What I just did was log on to the nsandi premium bonds website. Clicked "prize history" and there was an "October: £50" listed.
Whether that's been visible on the website since the 31st I don't know, I only just checked now.