Intonation question

The new uke is all strung up, still figuring out how slot the nut right so I don't get a buzz in my C string but the real question I have is about the intonation as I go down the frets. When it's in tune +/- a few cents when open stringed, it is consistently 15-20 cents sharp frets 1-4 in half step increments but on fret 5 it jumps a full note then back to half steps pretty much dead on the rest of the way up the scale. Any ideas? Is this normal intonation? how close is considered acceptable?
I laid up the plan drawings against the fret locations and it seems good, the lines fall on the frets, maybe not dead center on them but within the fret width. The fret slots were all cut by hand without a jig so I expected some tiny variations.

If I get you right you are figuring your fret location from the drawing? The drawing may not be perfect. I use the fret calculator at http://www.stewmac.com/fretcalc.html and have not had problems. Why not go there and enter your info and print it out and check your fret placement. Frets really have to me marked out and cut well with the short scales we are using for ukuleles. Much easier to do in millimeters.

Your right- the drawing was off a bit. Using my digital I/O micrometer I measured the fret spacing. All are within .003 of an inch except #5. Its a full fret width to close. Not much I can do about that now, I will live with it but it sure teaches me something. Nothing like a first build!