Yes, you are likely experiencing an intonation problem. Like when you sound an open E-string and then play the same string on the 12th fret, and they are not precisely one octave apart?
If this is the case with new a new set of strings, then you need to adjust the intonation slightly. It involves moving the bridge saddle towards the nut or away from it to shorten or lengthen the string. This is a standard issue when you change string gauge and it's something you really should learn to do yourself - it is not at all hard once you know how.
If you have old strings, then you will need to change to a new set first. And beware, old can be anything from a couple of weeks old to a month or three. Getting fresh strings on a regular basis is just one of those things you will need if you want to be considered a guitar player and play on a regular basis.
When grime starts to build on the string and corrosion sets in, then the string starts to vibrate unevenly - and your intonation goes out the window. If you don't clean your instrument and strings after each time you have played - and you have sweat and oil which "eats" strings - then this can begin after a couple of hours of playing.
Use coated strings, always clean your guitar and strings on a regular basis, and you can extend strings life considerably.
If you haven't changed strings for a while and you put on a fresh set, then you will need to clean the fretboard thoroughly first. If not then the grime and dirt on the fretboard will kill your new set of strings almost instantly.
Like I said, basic adjustment and maintenance is something which goes with the territory. You can either pay someone to have it done or learn how to do it yourself - and save money. If you feel like it, you can read more about it below.