IMO, if its your child's first time in a group setting, its par for the course. If it happens at 2 in dc, or at 4 or 5 in school, your child is getting exposed for the first time to all kinds of new viruses and bugs. It takes time for the immune system to cope. Honestly, our first winter in daycare was like having the black plague in our house. The age of the kids is part of it too. There were always more bugs going around in the toddler room because kids were more likely to lick things, put their fingers in everything, touch everything. As they get older, there is a bit less of that, also they are learning to wash their own hands more thoroughly, etc.
Last winter we did some preventative homeopathics for our DD on our naturopath's recommendation, and she had like 2 minor colds all winter.