i have a good sense of rhythm and no problem playing in tempo. Yet when i practice the g major scale, I'm like swinging the beat. So instead of play straight eight notes, I'm playing a dotted eight then a sixteenth notes.

Any suggestions on how to fix this, its like a mental thing.
When I play quarter notes right along with the click its fine.

Note that I am playing with a metrodome.
My guess would be your getting bored so your spicing it up, that is one of my biggest problems when practicing. You just need to make a mental effort to keep in time.

Edit : Spelling
Quote by Zaphod_Beeblebr
Theory is descriptive, not prescriptive.

Quote by MiKe Hendryckz
theory states 1+1=2 sometimes in music 1+1=3.
ok then well the next possibility is that ur brain seizes when u jump to the next string and its just not rendering right of what ur meant to be doing

slow the metronome down start extremely slowly,