Pure amino acids intake are ok. I would only worry about taking in too much protein (depending on your height and weight). If our body does not use it, the protein gets stored as fat.
the fact that those 3 ingredients are components (in part) of aspartame does not mean you are ingesting aspartame if you ingest the individual amino acids. phenylalanine and aspartic acid are important amino acids that are found in many, many foods and are actually incredibly important for protein and muscle synthesis. i would be more worried if your food contained formaldehyde, as that is an extremely toxic and dangerous substance that is used to preserve animals in research laboratories. your body will not synthesize aspartame from the components in your protein shake - rest assured! amino acids are important to take in the correct proportions - i.e. it's not usually helpful to take a big dose of just one or two of them (unless there's a specific medical need, of course) because they work in conjunction with eachother to benefit the body in myriad functions. as long as you are taking an appropriate amount of protein daily and the amino acids are in proportions that mimic our dietary need, you can feel ok eating your protein shake.