Yes, this could be normal. Different reasons might explain this:
String Tension Longevity
If you have never restrung your racquet before or have played long hours of tennis with the same strings, it is normal that your freshly restrung racquet seems tighter. Although some types of strings like natural gut preserve their tension over time well, all strings loosen up as time passes and hours are spent on the court. Sergetti stringing offers a string tension lasting up to 3 times longer than that of a conventional stringing.
The Sergetti Sensation
The Sergetti tension equivalence will give a different sensation than conventional strings. This is the direct result of our unique process: since tension distribution is uniform and efficient, your reference points are no longer the same. For this reason, a short adaptation period may be required.
Once adapted, you will be able to determine if your chosen tension perfectly fits your personal needs to maximize your Sergetti experience.
In case you have to get a new Sergetti Tension Sheet with a lower tension, your Tension Sheet giving you a too tight feeling is not lost. At times of the year when temperatures are higher, the stringbed relaxes more. So, for example, a racquet strung at 54 lb could offer sensations as if it were strung at 53 or even 52 lb.
Calibration of Stringing Machines
There might also be a slight variable between tension entered on the numeric keyboard of the machine and the real tension applied on the string. For example, if the tension prescribed is 57 lb but the real tension applied is 60 lb, you would have the impression of playing with a 60 lb strung racquet. The stringing machine calibration may differ from one stringer to another, so because of this, the tension may be lower or higher than it is should be.