Bon...this sounds dodgy as hell mate.
I have recently (last week or two) had more than two grand go through my paypal account with no problems whatsoever. I to have been a regular user of paypal for a few years aswell and the worst I got was last week when I got a email saying that my account was over the paypal limit and they basically washed there hands of any responsibility to pay me back the money if they went into liquidation
(had a email saying as much).
Needless to say I have withdrawn the funds to the safety of my savings account now untill I need to use them.
I would have thought that if it was a standard/compulsary measure that they take with irregular activities or whatever then I would be a prime candidate for investigation due to the amount of transactions and funds hitting my account. As of this moment in time though....nothing
Hope it pans out well for ya fella.
-ChEf