Ticking sound tundra

We own a 2000 Toyota Tundra–90,000 miles–obviously not used hard. When we turn on the ignition, we hear a ticking sound–sounds like it might be coming from underneath car passenger side. The sound seems to disappear as we drive it. Any ideas what it might be? Toyota service person told us it might be exhaust manifold and estimated maybe 2K to fix it.

Probably the exhaust pipe heating up. This is normal.