Terrorists have targeted planes since at least the 1970s and used them in some of the most spectacular attacks since then. I am not sure how the recent crashes (none of which have yet been determined as being related to terrorism) would make them more likely to try that option. They've been trying all along. You were no safer on a plane two weeks ago than you are now.

Statistically, it's pure coincidence that you had these incidents in such a short time period.