Question about a possible tipping faux pas

Important point to note - I live in the UK, servers get minimum wage, so tipping is less of a thing.

Yesterday I was out for a meal in a busy restaurant. Not a TGIChilibees but one of those with delusions of grandeur. Not my choice but anyway.

We had a nice server and I always tip anyway, having been a server myself. When it came to pay he was greeting customers so someone else came to take our money. I tip in cash so the servers don't lose anything to credit card fees or have to declare it in tax. When the other staff member took the card he didn't notice the tip. I didn't want the tip to get swiped or to go into the back pocket of someone else (some places in the UK do tip pools, some don't, so it's better just to give the person the tip). As we were leaving our server was at the bar so I took up the tip with me, said thanks very much and left the tip beside him.

My friends said that after I walked out the guy who took our payment (i.e. not our server) lifted the tip from the bar with the most furious expression on his face. I can't figure out why he was pissed off - the tip wasn't for him, and if it was a pooling situation then our server would have had to pool the tip anyway because there were three or four members of staff around when I handed the tip to our original server.

Any thoughts? Did I do something majorly wrong or was that guy just in a snit?