Could be the cap, the newest is 04; or it could merely be the car heat cycling and burping out air introduced while the coolant tank was replaced.
I had a bit of trapped air after doing my coolant tank, and just drove around for a week with the bail lifted on the top of the tank. No problems since.
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Six speed 2000 Boxster S
Arctic Silver on Metropol Blue | LN Dual Row IMSR | Arctic Silver console, spoiler frame & bumperettes | Crios mod | Technobrace | RoboTop module & modified convertible top relay for one-touch roof operation
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