speaker rattle: old speakers or other issue?

I have (had) 3 Boston Acoustic THX speakers for my LCR. In about a month's time two of them started to rattle. The system has never been even up to of half of its max volume. But the speakers are about 25 years old.

Shall I just chalk these rattles to just that the speakers are old?

Or is there something else I should be looking out for? Like amp or pre-amp issues?

When the first speaker went, I wasn't ready for a full speaker replacement and just got an ok center speaker. Before buying decent LR speakers, I thought prudent to check if the general opinions were old speakers or if there is something else that might be going on. It would be sucky if the new speakers got blown, too.

Thanks.