Probably neither, although it is possible to bend a chainring by pedalling hard.
Most probable cause, unless the chainring has gotten dinged sideways somehow is simply manufacturing tolerances.
The crank might not sit entirely perpendicular to the BB, or the chainring flats on the carrier aren't machined to the exact same level, or the chainring spacers aren't exactly the same size, or....

Your options are:
- ignore it if it isn't affecting shifting
- remove the chainring, check that it's flat. If it isn't, attempt to straighten by use of rubber or wooden mallet, or by bending.
- If the chainring is flat, shim the chainring flats on the carrier until frustration or the desired degree of trueness is ahcieved.