brake light bulb busted twice

Is this common or a sign of something? Twice now the same one(left brake-top bulb) I found with the top half of the glass portion blown off and purple. I understand the discoloring, but busting? Right side was not working, temp fixed, but not working again. It's on the list. The first time the left blew, the right was working I believe but can't swear. Just coincidence in 2 bad bulbs or something else? Not using the 1157, using 7528, just fyi.

Have any crop circles appeared in the county?






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Must be something odd going on: A. I've never seen low-voltage light bulbs blow part of the envelope off, and B. I'm running the original brake light bulbs after 11 years. I have seen 120 v bulbs over-heat (mainly movie projectors) and one side bulge until it pops. Since your bulbs are popping on the top, maybe something is reflecting heat back to the bulb.

crop circles?