1985 VF500 noisy cam chain tensioner

85 interceptor 500 with 30k miles. Brought it to a shop to clean carbs, ended up having to replace the whole carb assembly. Had them change oil and inspection while it was there. New carbs worked great, started right up and ran fine. For about 50 miles.

Then suddenly developed loud clacking noise from right front cylinder that increased with revs. Brought it back to shop, they're saying cam chain tensioners are shot, and quoting me 6 hrs of labor.

And thoughts or ideas? Could it be an oil issue, strange that it went 30k then developed the prob immediately after they serviced it.
Thanks