Cinammon bun made with leftover sweet sourdough dough

I got some leftover dough from another recipe, so I rolled it up with plenty of cinammon, brushed it with egg and...off it went! "Sweet sourdough buttery stick", plenty of butter and milk in there... 100% sourdough. The dough was slightly under-proofed, it could have been lighter, but it didn't have any hint of the sour starter,

Done