Sounds like it. But any failure that causes this behaviour in an engine mount should be easy to spot. If they look fine, the problem may be somewhere else. Here's a tip, fold a piece of regular photocopy paper in half, and insert it between the gears, now tighten down your engine. Now remove the paper. Mesh should be perfect, but make sure your engine is well seated and there isn't a genuine problem with the mount before you run it.