I researched this out three years ago - and you got 30 minutes of googling and writing this 'cause I forgot the details
do I need to scrape it off the window seams
Id printed on the tube says: 626 Aluminum-5...
No sir, you don't need to change out the 'bead' seals, its just more more likely to loose its grip on smooth surfaces after a dozenteen years. Its own exposed surface will not look like a metal smooth surface, especially after aging a couple of years. The added silica helps it key into porous surfaces and take compression loading say from sun-heated skyscraper facia and trim.
The 636 is smooth; the 626 is textured with silica sand so it will not allow clamped metal overlaps (window frame installations not refreshing outer seam seals) to compress together to near 'metal-to-metal' dimensions.
Trempro 636 is the product with the smoothest consistency - that is the stuff that is still 'wet' inside the lap joints 35+ years after assembly on my trailer. The 636 has more 'rubber' and less solvent so less shrinkage (VOC (g/L) TremPro 626: 85 TremPro 636: 61)
[A/S] Final word on Vulkem choices
<-- thumbnail explanation of Airstream caulk history