Strange that they put your account on verification after years of activity. It's likely that you completed some big surveys and they were waiting for payment from advertisers before paying you out.I just off of my "verification" period. I've been a member for 3 years. no explanation, and exactly 60 days. I had to ask 2 times to be unfrozen and agin to get my referral's earnings credited.....I only do surveys, so I had no reason to be verified and then 60 days?
The other possibility - you had some reversals with surveys and they wanted to make sure the reversals wouldn't continue.