This one is very hard to say. We likely we have needed to troubleshoot the issue live to attempt to give a root cause. Were the ports LACP blocked or blocked in spanning tree (two different things). Did you try to console to the 7250 during the issue? It could be high cpu, loop, etc. With that said, that is purely speculation. I would recommend opening a support case (see my signature) if this happens again or if you would like a proper investigation.
Ben Beck, RCNA, RCNI, Principal Technical Support Engineer