Not an opinion but merely a guess- all will be fine. Transmission shift forks and dogs are really quite robust and unless subjected to repeated and specific misuse (shifting 20% of the way into second gear, applying all engine power and having the dogs jump back into neutral is the most common way to badly abuse the transmission). Besides that, 5th gear does not get anywhere the abuse that, for example, second gear sees due to greatly reduced torque in 5th, and actually jamming the bike into gear is better than trying to ease it in (Easy Boys!) and causing the dog ears to, well, dog ear :-)
I think you will be fine but again, just a guess.
Brian
I'm with Brian here. I've had this happen several times, also in 5th gear on a 2006 Kawasaki Z1000 that I purchased brand new. The sound it makes when you finally do get it pulled in is gawd awful...lol. After it happened a couple times, I started coasting to a stop on the side of the road before popping it back in gear. I adjusted the shift lever down a little and focused more on good solid shifts, and the problem rarely returned...I think once in a while when I got lazy and didn't pull hard enough on the shifter, it would happen. I put another 20k miles on that bike and never had an issue.
The 2005-2006 Kawasaki ZX6R/636 is known for having a weak 2nd gear...the dogs get rounded off, and it will pop out of gear under heavy abuse (track riding or stunting, etc). On the street, they are rarely ever an issue...but once abused, they do seem to be problematic. I changed the transmission/shift drum/forks in a friend's 06 a couple years ago and it has been fine ever since....even under heavy abuse.
As Brian said...I wouldn't worry about it unless it continues to happen.
JMTCW,
Rem