There is definitely a chance that the shot will cause flu-like symptoms. Personally, I haven't had an innoculation since I had the mandatory MMR innoculations before High School because I'm very, very, very frightened of needles. I've been living in dorms for the last two and a half years and I've not had anything more than a minor cold in that time though, so I'm not worried about it. The way I see it, if you have a tendency to get sick, then the shot is probably a good idea since even if you have a reaction you can basically control when you have it (by controling when the shot is) and then you don't have to worry about getting the flu later on. However if you don't usually get sick, then don't worry about it.
ZV