This is not necessarily a negative. Different kinds of meditation techniques may be more conducive to one state or the other. In particular, some Breath Training techniques (such as those in the Relief category) may be more likely to produce a Calm state, while others (such as those in the Revive category) tend to increase Focus.
Everyone is different: you may find that some meditations and breathing techniques impact you in a unique way, as compared to another person doing the same sessions.
There are always other variables at play, too - if you’ve had a particularly stressful day, or an extra cup of coffee, or you were distracted by loud noises during your meditation — all these things can potentially impact your heart rate. Some days, it might simply be harder for you to relax and focus. Try recording these types of observations in the Reflection section in your post meditation results after you complete your meditation, where you can reflect on your experience: you may begin to notice patterns.
Research shows that ensuring that you take a little time in your schedule to meditate regularly is even more important than how you felt during it, or even how long you meditated for. Consistency is key. Making meditation a part of your regular routine helps train your brain to respond to it and unlocks numerous mental and physical health benefits.