I ran some "post-dictions" for Rehoboth, MA, for 4:00 AM EDT this morning (Sunday, March 30). I didn't come up with an obvious candidate, but I'm not sure how much leeway to allow in the time, RA and Dec, etc. In the Clarke Belt area, along with active and dead payloads there are many upper stages of launch vehicles which could be tumbling as you observed. There are also such objects in geosynchronous-transfer orbits (GTO) that are quasi-stationary when at apogee. Did you estimate a magnitude of your object? Can you narrow down the time and sky position?
At about 5:00 AM I get an out-of-service DSP satellite. Those are spin-stabilized and typically flash about every 2.5 seconds. But the time is an hour off, of course. There's no official data for it, and the amateur elements are 60 days old, but I tend to think that it would be only a few minutes off, not a full hour.
By the way, an object in orbit is of course traveling in a very stable manner. Could you attribute what you describe as irregular motion to vibrations of the scope, eye movements, or anything else like that?
Ed Cannon - Austin, Texas, USA