re-tighten stretch bolts?

[johnnybronco]

I replaced all the gaskets last year. I took my time and did everything by the book, but it was my first time so who knows what I may have missed. It's been running great, good gas mileage and power for 10 months now so I'm not really that worried - I just add a cup of water to the radiator every month and a quart of oil every 2000 miles or so. but I do have some brownish gunk floating on the top of the oil when I drain it for an oil change.