Are you sitting fairly close to the bike while you are there? My bike won't recognize the fob properly either if it's been within range for an extended amount of time.

 

Someone had this same issues as well at at restaurant or someplace (can't remember). I think it's the electronics at the pub, like a WiFi or something that's causing an interference. Park farther back next time.

 

Dealer is ordering a new FOB, I had the same issue multiple times, alarm would go off and unable to start, then it would work again and start up, then finally after a few weeks it wouldn't start at all 100 miles from home and I had already put a new battery in after the first few encounters! Took the FOB apart and pushed down on the battery and it was working with pressure applied to it. Tore a piece of rag and put inside the FOB to keep the pressure down and problem temporary solved.

 

Here's how it works.
https://apps.fcc.gov/oetcf/eas/repor...c_id=L2C0028TR


The bike sends out an interrogation signal at a very low frequency of 125 kHz when the ignition is switched on. Your fob receives this and responds back at 433.92 MHz with a binary coded pulse train. If the codes match, voila, your security system disables and your engine will start. Pass Card swipe readers also work at 125 kHz and a huge number of wireless alarm systems operate at 433.92 mHz. So there's your problem, your too close to one of those operating systems.