Don't panic.... but don't do that again! Make sure the buds are not touching each other, make sure the fan is not blowing directly on the buds and things will be fine. If you ever find the buds are too dry in the future, jarring them up and putting a piece of lettuce in the jar with them will raise the humidity in the jar just enough to soften the buds slightly and should be enough to bring them back to where you want them to be. It's much the same as using a piece of bread to soften up rock hard brown sugar... you can use bread as well BUT that will tend to add a different taste to the buds and therefore isn't something you'd really want to do.... using lettuce is safest because there's no overall flavor/smell to lettuce.
As a rule of thumb, what you want to try to achieve when drying is 60F, 60% humidity and have a fan blowing air gently AROUND the buds, not directly on them... that should give you a nice, long, slow dry time.
Good luck....