Nice one, fingers crossed it was that. mine was lifting near the little locating pin the gutter rubber trim attaches to. Mine was obvious as the paint had cracked.
Id go and take a photo for you but currently isolating due to covid!!
@dan1 That's brilliant Dan, thank you! Think you might have saved me a load of work as got Paul Bladerider929 coming down today to help me take out the headlining so might just take off the roof rails and gutter trim and have a look there first.
Dave I had a similar problem and it was the seam sealer under the gutter trim that had cracked and was letting water in.
I picked it out with a screwdriver where i could see gaps and filled it in with some PU sealant and its been good ever since.