I don't know whether you should be worried. I do know that this type of behaviour is antisocial though - it promotes unfairness - people that made reservations or are waiting outside have to wait longer because someone has bribed their way in.
Maybe next time someone will pay $50 - because it is not something to worry about,no? - and you'll have to wait 15 minutes to get a seat.
Along similar lines, it's unfair to get pictures professionally taken, or to use cologne or makeup. Sorry, mating has always been an arms race to some extent, and that's not going to change.
Should I be worried that my relationship 'started with bribery' because I handed the maitre'd $20 to get us a good table?